Unusual acetylated flavonol glucuronides, oxyphyllvonides A−H with renoprotective activities from the fruits of Alpinae oxyphylla

Abstract

As a widely consumed spice and Traditional Chinese Medicine, Alpinae oxyphylla has been used to treat conditions such as diarrhea, ulcers, dementia, and enuresis. Fruits of A. oxyphylla were phytochemically studied and the bioactive constituents against renal fibrosis were identified. Eight previously undescribed acetylated flavonol glucuronides named oxyphyllvonides A−H (1−7 and 10), two known acetylated flavonol glucuronides (8 and 9), together with seven known flavone glycosides (11−17) were isolated from the fruits of A. oxyphylla. Among them, flavonol glucuronides were discovered in Zingiberaceae for the first time. The planar structures of 1−7 and 10 were determined using HRESIMS and extensive spectroscopic techniques (UV, IR, 1D-NMR, and 2D-NMR). The absolute configurations of the sugar moiety in these compounds were determined by using LC-MS analysis of acid-hydrolyzed derivatized monosaccharides. Biological evaluation showed that 7–10, 13, 14, 16 and 17 inhibit renal fibrosis in TGF-β1-induced kidney proximal tubular cells. In addition, 7, 8 and 14 were superior to nootkatone in inhibiting Fibronectin expression. The finding has significant relevance to our ongoing research on the anti-renal fibrosis activity of A. oxyphylla.